1. Field of the Invention
The present invention relates to a method of manufacturing a connector for a flat cable which is applied to an electrical connection device which receives and transmits electrical signals between a rotary body connected to a steering wheel and a fixed body connected to a steering column in a steering mechanism of a vehicle, for example, a connector for a flat cable and an applying member for applying ultrasonic vibrations to be used for the method.
2. Description of Related Art
When a kind of an electrical connection device transmits signals from a flat cable wounded around a rotary body to an the outside by a connector, as a connection means between the flat cable and the connector there is used a connector for the flat cable which is connected to a tip portion of the flat cable.
Conventionally, a connector for a flat cable is composed as the following. Plural connector terminals are exposed on obverse surfaces and reverse surfaces and are insert molded in a first holder at a pitch equal to that between conductor portions of the flat cable. Plural bus bars are exposed on obverse surfaces and reverse surfaces and are insert molded in a second holder assembled to the first holder at a pitch equal to that between the conductor portions of the flat cable. The conductor portions of the flat cable are interposed between the plural connector terminals and the plural bus bars, and are collectively welded with the connector terminals and bus bars by ultrasonic welding, thereby being connected together.
In this case, the plural connector terminals are insert molded in the first holder so that are parallel to one another and are each separated therebetween by insulation walls which are integrally formed to the first holder.
In the ultrasonic welding, the conductor portions of the flat cable is set, and is positioned between the connector terminals and the bus bars. In this state, an anvil is putted under the connector terminals and an ultrasonic applying member which is to be inserted between the insulation walls is pressed on bus bars from upside. Ultrasonic energy is applied to them, and thus the connector terminals, the conductor portions of the flat cable and the bus bars are collectively welded by ultrasonic welding.
However, according to the conventional connector, a width of a contacting portion with a bus bar in the ultrasonic applying member is narrower than that of the bus bar, and if the ultrasonic applying member is off determined position relative to the bus bar, it cause connection strength to be degraded at the ultrasonic welding. Thus, a high work precision is required at the ultrasonic welding.
The connector terminals are insert molded in the first holder with neighboring insulation walls, the insulation walls ensure an insulating state of a circuit of each connector terminal. However, it is easy to appear a phenomenon that excessive resin of the insulation wall mounts on the connector terminal when forming the connector terminal, and the phenomenon causes connection strength to be degraded at the ultrasonic welding.